As a method for measuring a blood pressure of a living body in a Non Invasive manner, there is widely used a method in which a pressure unit such as a cuff or the like is set on a specific region of a living body, and an artery and a circumference thereof are pressurized by the pressure unit to measure a blood pressure. As blood pressure measurement devices that measure a blood pressure in a Non Invasive manner, there are devices such as a blood pressure measurement device based on a microphone method for detecting a Korotkoff sounds using a microphone, and a blood pressure measurement device based on an oscillometric method.
These blood pressure measurement devices stop a blood flow in an artery in a specific region (measurement region) and thereby measure a systolic blood pressure that is a blood pressure in a course of heart contraction. Therefore, it is necessary for the pressure unit to apply, to the artery, a pressure higher than a systolic blood pressure (a systolic blood pressure value, a maximum blood pressure, or a Systolic blood pressure, hereinafter, expressed also as an “SBP”). However, a pressure applied by the pressure unit is frequently a burden on a subject to be measured.
To reduce the burden, PTL 1 or PTL 2, for example, discloses a blood pressure measurement device that reduces the pressure for measurement.
PTL 1 discloses a blood pressure measurement device capable of measuring a blood pressure without using a pressure unit. The blood pressure measurement device calculates a characteristic value associated with a blood pressure on the basis of a pulse wave measured in a non-pressure state and estimates a blood pressure on the basis of a correlation between the calculated characteristic value and a blood pressure value.
Further, PTL 2 discloses a blood pressure measurement device that measures a systolic blood pressure on the basis of a wave height value of a pulse wave by using a cuff. The blood pressure measurement device estimates a systolic blood pressure via coefficient transformation of a wave height value of a pulse wave measured at a cuff pressure lower than a systolic blood pressure.